SIMULATING METEORIC AND MIXING-ZONE DIAGENESIS OF MARINE CARBONATES VIA A TWO-DIMENSIONAL REACTIVE TRANSPORT MODEL

As observed on modern carbonate platforms, meteoric and mixing-zone diagenesis is a common process in shallow water carbonates. Most preserved carbonates prior to the Cenozoic were deposited in shallow marine environments and were, therefore, susceptible to meteoric and mixing-zone diagenesis. However, our theoretical understanding for how geochemical compositions of carbonates change during diagenesis is still limited. We will present a new two dimensional (2D) reaction transport model coupled with a 2D hydrology model of coastline to understand the kinetics of geochemical variations during carbonate diagenesis. Using this model, we have reproduced geochemical variations in both modern and ancient (especially Neoproterozoic) carbonate profiles. This work challenges several previous views on the geochemical effects of meteoric diagenesis. Further, given that the model can reproduce not only the stratigraphic trends of but also the relationships between many geochemical records, this works bolsters the case that many geochemical records previously linked to extreme global biogeochemical cycle perturbations are instead linked to carbonate alteration. This work calls for a reevaluation of the effects of diagenesis on shallow water carbonate successions.